566 Notices of Memoirs — Prof. 0. C. Marsh— Age of Fossils. 



"■ This brings up an important point in Palaeontology, one to which 

 my attention was drawn several years since ; namely, the com- 

 parative value of different groups of fossils in marking geological 

 time. In examining the subject with some care, I found that, for 

 this purpose, plants, as their nature indicates, are unsatisfactory 

 witnesses ; that invertebrate animals are much better ; and that 

 vertebrates afford the most reliable evidence of climatic and other 

 geological changes. The subdivisions of the latter group, moreover, 

 and in fact all forms of animal life, are of value in this respect, 

 mainly according to the perfection of their organization or zoological 

 rank. Fishes, for example, are but slightly affected by changes that 

 would destroy reptiles or birds, and the higher mammals succumb 

 under influences that the lower forms pass through in safety. The 

 more special applications of this general law, and its value in geology, 

 will readily suggest themselves." 



In the statement I have quoted, I had no intention of reflecting in 

 the slightest degree on the work of the conscientious pal^obotanists 

 who had endeavoured to solve the problem with the best means at 

 their command. I merely meant to suggest that the means then 

 at their command were not adequate to the solution. 



It 80 happened that one of the most renowned of European 

 botanists. Sir Joseph Hooker, was then in America, and to him 

 I personally submitted the question as to the value of fossil plants 

 as witnesses in determining the geological age of formations. The 

 answer he made fully confirmed the conclusions I had stated in my 

 address. Quoting from that, in his next annual address as President 

 of the Royal Society, he added his own views on the same question.^ 

 His words of caution should be borne in mind, by all who use fossil 

 plants in determining questions of geological age. 



The scientific investigation of fossil plants is an important branch 

 of botany, however fragmentary the specimens may be. To attempt 

 to make out the age of formations by the use of such material alone 

 is too often labour lost, and must necessarily be so. As a faithful 

 pupil of Goeppert, one of the fathers of fossil botany, I may perhaps 

 be allowed to say this, especially as it was from his instruction that 

 I first learned to doubt the value of fossil plants as indices of the 

 past history of the world. Such specimens may indeed aid in 

 marking the continuity of a particular stratum or horizon, hut 

 without the reinforcement of higher forms of life can do little to 

 determine the age. 



The evidence of detached fossil leaves and other fragments of 

 foliage that may have been carried hundreds of miles by wind or 

 stream, or swept down to the sea-level from the lofty mountains 

 where they grew, should have but little weight in determining the 

 age of the special strata in which they are imbedded, and failure to 

 recognize this fact has led to many erroneous opinions in regard to 

 geological time. There are, however, fossil plants that are more 

 reliable witnesses as to the period in which they lived. Those found 



1 Proceedings of the Eoyal Society of London, vol. xsvi (1887), pp. 441-3. 



